A superconducting cable includes a cable core formed by laminating, for example, a superconductive conductor layer, an electrical insulation layer and a shield layer around a former, and a thermal insulation pipe of vacuum double pipe structure to accommodate the cable core. Inside of the thermal insulation pipe, liquid coolant having a very low temperature (for example, liquid nitrogen) is circulated to cool the cable core.
When the superconducting cable is used as a power supply line, the superconducting cable needs to be installed from a power supply to a distant power consuming area. However, a length of a single cable is limited due to reasons relating to the production and transportation of the superconducting cable. Therefore, a multiple superconducting cables need to be connected with each other when a cable having a long length is installed.
A tape-like superconducting wire in which a superconducting layer is formed on one side of a base plate is becoming general as the superconducting wire constituting the superconducting layer of the superconducting cable. When such superconducting wires are connected with each other, the superconducting wires need to be connected with each other such that the superconducting layers face each other.
However, since the superconductive conductor layer of the superconducting cable is generally composed of the superconducting wires with the superconducting layers facing outward, the superconducting wires which each constitute the superconductive conductor layers of the superconducting cables cannot be connected with each other as they are.
In Patent Document 1, when superconducting cables are connected with each other in a state where superconducting wires of each superconductive conductor layer face up (outward along the radial direction of the superconducting cable), superconducting wires for connection are attached therebetween in a suspended state such that the superconducting layers face down (inward along the radial direction of the superconducting cable) to realize a connection.
In Patent Document 2, a superconducting wire is proposed which includes superconducting layers on both sides thereof by applying the base plate sides of superconducting wires to each other.